Lighting system control for ophthalmic examinations

ABSTRACT

A control system coordinates fixture lighting in an ophthalmic examination room with the selection by a physician of a particular ophthalmic instrument with which a patient is to be examined. Selection of a portable instrument operates the necessary switches to automatically power the instrument and establish the optimum ambient conditions of room light for conducting the examination with the instrument selected.

United States Patent [191 Nevyas et al.

[ 1 Apr. 3, 1973 LIGHTING SYSTEM CONTROL FOR OPHTHALMIC EXAMINATIONSInventors: Herbert Nevya s, 210 1 Walnut Street, Apt. 1301,Philadelphia, 19103; Wilfred Klein, 511 Rock Glen Drive, Wynnewood, bothof Filed: Apr. 28, 1971 Appl. No.: 138,225

US. Cl. ..35l/1, 240/2 S, 240/52 R,

315/362, 351/38 Int. C1.......A6lb 3/00, H05b 37/02, F2lv 33/00 Field ofSearch ..35l/l, 16, 36, 37, 38, 17;

240/2 S, 52 R; ZOO/61.48; 315/362 [56] References Cited UNITED STATESPATENTS 1,625,075 4/1927 Clement et al. ..35 l/38 X 1,598,606 9/1926 Dey..35 l/l6 X Primary Examiner- Attorney-Seidel, Gonda & Goldhammer [5 7]ABSTRACT 10 Claims, 9 Drawing Figures 5 E S E 5 ET PRGIECTOI LAMP HUScLl1 88b OK 6 [fps/0 II-IIKII FurAflaN STIMIE WAT] PATENTEDAPRS 19753,724,931

SHEET 2 BF 6 NURSES F/G.Z

5m MON /3/ INVENTORS HERBERT J. NEVYAS W/LFRED KLEIN Mfmw ATTORNEYSLIGHTING SYSTEM CONTROL FOR OPHTHALMIC EXAMINATIONS DETAILED DESCRIPTIONThis invention relates to a control system that coordinates fixturelighting in an ophthalmic examination room with the ophthalmicinstrument being used by a physician examining a patient.

Equipment for performing complete ophthalmic examinations includes suchportable instruments as an 1 ophthalmoscope, a retinoscope, atrans-illuminator, various muscle lights, a gonioscopic illuminator, anda indirect ophthalmoscope, for example, and such standing instruments asa slit lamp and a keratometer. These instruments require severaldifferent voltage levels, such as 3, 6, 9, or 12 volts a.c., as well as110 volts a.c.; and each instrument is used under different ambientlighting conditions. Some parts of the ophthalmologic examination arebest performed under conditions of full room lighting,some underconditions of dim lighting, and some in total darkness. For mostexaminations, it is best to stabilize the position of a patients eyes byproviding fixation lighting at a remote location in the room. For someexaminations, this fixation lighting is best located above the patientseye level, while for other examinations, such fixation lighting is bestpositioned at eye level.

To secure the optimal room lighting and fixation lighting conditions inpreparation for using a particular portable ophthalmic instrument, thephysician is required to switch on the instrument, adjust the roomlighting, and switch on the proper fixation light. This, of course,requires time and concentration on the part of the physician anddetracts from the primary purpose of the examination. In the event thatthe examiner neglects to adjust either room lighting or fixationlighting or both, the examination will be performed under less thanoptimal conditions. It is therefore the primary object of the presentinvention to provide a lighting system control that will save theexaminer time and increase his productivity by eliminating the necessityfor constantly coordinating room light with the instrument being used,while at the same time improving the quality of the examination byinsuring optimal lighting conditions for each phase of the eyeexamination.

Briefly, the lighting system control of the present invention includes acontrol panel into which the various ophthalmic instruments are pluggedto secure electrical power, and hangers for holding the instruments whennot in use. Switches associated with the hangers actuate circuit meansin the control panel when an instrument is removed from its hanger forpowering the instrument and for controlling the ambient room lighting toprovide optimum lighting conditions for use of the particular instrumentselected. For example, use of a direct ophthalmoscope requires acompletely darkened room; but, examination is facilitated if the patientfixes his eyes on a remote spot just above his eye level. The presentsystem responds to removal of the direct ophthalmoscope from its hangerby automatically powering the instrument with the required low levelA.C. voltage, by turning off the room light, and by turning on a lowlevel fixation light at the opposite end of the room from the patient.On the other hand, the use of a retinoscope requires a dimly lightedroom, and an eye level fixation light at the opposite end of the roomfrom the patient.

These results are achieved by appropriately located switches operatingon the circuit means in the control panel. In each instance, returningthe particular instrument to its hanger will cause the ambient lightingcondition to revert to its former status before the instrument wasremoved from its hanger. The circuit means of the control panel isconstructed and arranged so that the operation of the circuit means inresponse to the removal of an instrument from its hanger can be modifiedby manual override switch means. The present invention thus relieves theexaminer of the task of adjusting either room or fixation lighting foreach of the examinations necessary for a complete ophthalmologic studyof a patient. Consequently, the examiner saves time and increases hisproductivity. Simultaneously, the quality of the examination is improvedbecause optimum ambient lighting for each phase of the eye examinationis provided automatically.

The features of this invention for which protection is sought arepointed out with particularity in the appended claims. The inventionitself, however, both as to its organization and method of organization,together with further objects and advantages thereof, may best beunderstood by reference to the following description taken in connectionwith the accompanying drawings, wherein like parts in each of theseveral figures are identified by the same reference character, andwherein:

FIG. 1 shows a typical wall mounted control panel andinstrument hangerbank;

FIG. 2 shows the back panel arrangement of the housings whose frontpanels are shown in FIG. 1;

FIG. 3 is a schematic showing of a slit lamp instrument and plugtherefor;

FIG. 4 is a schematic showing of a receptacle suitable for an indirectophthalmoscope including a plug suitable for mating with a suitablesocket in the panel shown in FIG. 2;

FIG. 5 is a schematic showing of a typical plug associated with thefixation, muscle and bunker lights;

FIG. 6 is an electrical schematic of the circuit means contained in thehousing whose front panel is shown at the top of FIG. 1;

FIG. 7 is an electrical schematic of the circuit means shown in thehousing whose front panel is shown at the bottom ofFIG. 1;

FIG. 8 is a modification of the circuitry shown in FIG. 6 to accomodatea remote station at which certain of the switches can be operated; and

FIG. 9 is an electrical schematic of the circuit means of a remotestation at which certain of the switches can be operated.

Referring now to FIG. 1, reference numeral 10 denotes one wall of anenclosed eye examination room. Such room (not shown) is illuminated byroom light 11 (FIG. 2) and is provided with three special 6 volt, A.C.incandescent lamps on the wall at the end of the room remote from theend of the room at which is seated a patient whose eyes are to beexamined. Blinker lamp 12 (FIG. 2) produces a blinking white light whenpower is applied thereto. It is useful in attracting the attention ofchildren during eye examinations. Muscle lamp 13 is positionedsubstantially at eye level with respect to a seated patient in theexamination room, and produces a steady white light when operated. Themuscle lamp is useful in providing a remote point in space upon which apatient can focus his eyes when being examined with the retinoscope.Fixation lamp 14 is also positioned substantially at ceiling level withrespect to a patient seated in the eye examination room, and produces asteady red light when operated. The fixation lamp is useful in providinga remote point in space upon which a patient can focus his eyes whenbeing examined with an ophthalmoscope.

Referring again to FIG. 1, wall defines the end of the room at which thepatient being examined is seated. Mounted in wall 10 are two metalenclosures or chasses (not shown) provided with separate removablepanels 15 and 21 mounted flush with wall 10. Panels 15 and 21 areconveniently located adjacent to the examination chair and are easilyaccessible by the examiner.. Instrument hanger panel 15 is provided witha plurality of hangers 16-20 specially designed for the instrumentsconventionally used for eye examination purposes. Such instruments mayinclude opthalmoscope II, retinoscope I2, trans-illuminator I3, musclelights I4 and I5, and Barkan light I6. Instruments other than these canalso be accommodated on instrument panel 15. Also mounted on instrumenthanger panel 15 are six rotary knobs Kl-K6, each of which isindividually associated with one of the six instruments as shown in FIG.1 and is used to adjust lamp intensity. Panel 15 is also provided with aplurality of sockets S12-S 16 which provide outlets into which thevarious instruments may be connected to the proper source of electricalpower.

When an examiner wishes to utilize the ophthalmoscope for examining apatients eyes, the instrument must be powered, and certain ambientlighting conditions must be established in order that the examination beperformed under optimum conditions. Such ambient lighting conditionsinclude total room darkness except for the illumination of fixation lamp14. The apparatus of the present invention responds to the removal ofinstrument II from hanger 16 by automatically operating the necessaryswitches to power the instrument and achieve the desired ambientlighting conditions. Knob K1 is used by the examiner to adjust theintensity of the lamp in this instrument.

Sometimes the examiners assistant must enter the darkened room whileophthalmoscopy is in process to perform some task such as obtaining achart or the like,

and it would be helpful to provide a dim light by which the assistantcould see well enough to complete his task without significantlyinterrupting the examination. For this reason, the circuit means of thelighting control system'provides a manual override for certain of thefunctions occurring automatically upon removal of an instrument from itshanger. The override in this case, is provided by pushbutton PBS onswitch panel 2]. Depression of this switch when the room light is extinguished, turns on room light 11 but at a reduced intensity. Rotation ofknob K11 on panel 21 provides a control for the intensity of light 11.When the examiner returns instrument II to its hanger 16, it will bedepowered, and ambient lighting will be restored to the state thatexisted prior to the removal of this instrument from its hanger.

When the examiner wishes to conduct a retinoscopy, and instrument I2 isremoved from hanger 17, the circuit means of the present invention willautomatically power this instrument, dim the room lamp 11 and switch onmuscle lamp 113. Returning instrument I2 to its hanger 17 will de-powerthe instrument and restore the lighting in the room to its initialcondition.

The removal of any of instruments I3-I6 from its respective hanger willautomatically provide electrical power of the correct voltage to theinstrument. The knobs K3-K6 may be used by the examiner to adjust theintensity of the lamp in the instrument with which the knob isassociated.

The bench mounted slit lamp I7, as shown schematically in FIG. 3, isprovided with plug P10 in place of its usual power cord. Plug P10 ismated with socket S10 which may conveniently be located on rear coverpanel 150 which closes the rear of the lower chassis in wall 10 whosefront is closed by instrument hanger panel 15.

When pushbutton PB11 is depressed by the examiner,

the circuit means of the present invention will automatically providepower to the slit lamp, and simultaneously dim room light 11.

The indirect ophthalmoscope I8 plugs into socket S18 (FIG. 4) associatedwith a separate control box (not shown) located adjacent to panels 15and 21. When instrument I8 is lifted from its hanger, the circuit meansof the present invention will automatically provide power at the propervoltage level to the instrument lamp, and simultaneously extinguishlight 11. The return of the instrument to its hanger will restore theinitial ambient lighting conditions.

In addition to the above-described instrument, it is conventional for anexaminer to have available a projector by which numbers and letters canbe projected on a screen in front of the patient. To this end, panel 210is provided with socket S8 with which a plug from a projector can bemated. Provision is also made for controlling a high-intensity lampuseful to an examiner when testing near vision or performing minorsurgery. Such lamp may be plugged into socket S9 in panel 210.

The circuit means by which the present invention achieves theabove-described operation is shown in detail in FIGS. 6 and 7 to whichreference is now made. FIG. 6 shows the circuitry in the chassis behindpanel 21; and FIG. 7 shows the circuitry in the chassis behind panel 15.The circuitry includes relay operated contacts; and the convention usedin this application for designating a relay and its associated contactsis as follows: a relay coil is designated by a capital letter, and thecontacts operated by the coil when the latter is energized aredesignated by the same letter but lower case. Normally open contacts areshown as a pair of spaced parallel lines perpendicular to a conductor;and normally closed contacts are shown with a diagonal lineinterconnecting the parallel lines of the normally open contacts.Energization of a coil will close normally open contacts associated withthe coil and will open normally closed contacts.

Assume that all instrument plugs are mated with their respectivesockets, that plug P1 is mated with socket S1 to interconnect the twochassis, and that power plug P7 is mated with a socket supplying voltsA.C., 60 Hz power. Also assume that each switch on panel 21 has thecondition shown in FIG. 6. In such case, power switch SW1 is open, andrelay coil A is unenergized. As will be seen, none of the sockets S2-Sl8will have power, and room light 11 will be extinguished. When pushbuttonP81 is depressed closing the two contacts associated with this switch,relay A is energized closing normally open contacts a1 and a2. As aconsequence of the closing of these contacts, A.C. power is applied totransformer T1 (FIG. 7) through terminal pins P and Q of plug P1 andsocket S1. In addition, 110 volts A.C. power is applied across contactpins 1 and 2 of socket S10 which mate respectively with contacts 12 ofplug P10 associated with slit lamp [7. A.C. power is also suppliedacross open terminals 1 and 2 of switch SW6 which controls theapplication of power to socket S9 into which a high intensity lamp isplugged. In addition, A.C. power is applied across normally opencontacts b associated with relay coil B thus preparing projector socketS8 to be powered when relay coil B is energized by the closing ofcontacts 1 and 2 of switch SW7. Lastly, A.C. power is applied throughnormally closed contacts c and d to socket S6 into which room light 11is plugged, thus turning on this light.

The flow of A.C. power through the primary of transformer T1 shown inFIG. 6 provides selective low order voltages across the secondary oftransformer T1. The secondary is provided with five voltage tapsproviding the following A.C. voltages: 0, 3, 6, 9, and 12 volts. Thevoltage cross-leads 22 and 23 derived from contacts L and G of socket S1is 12 volts A.C. Leads 22 and 23 are connected across lamp L1 in switchSW1 so that the closing of contacts 1 and 2 in this switch upondepression of the pushbutton has the effect of illuminating Llindicating that the power to the circuit means of the invention has beenturned on. Summarizing, the operation of the power switch willilluminate the lamp associated with this switch, will turn on the roomlight, apply the power line voltage to the slit lamp socket, and willprepare for the operation of the projector associated with socket S8 andthe lamp associated with socket S9.

To turn off the room light 11, pushbutton PB9 is depressed closingcontacts 1 and 2 and applying 12 volts A.C. to node 24. As aconsequence, lamp L9 associated with this switch is illuminated andcurrent flows through normally closed contacts 5 and 6 of switch SW8 andinto coil D. Normally closed contacts d are opened when coil D isenergized, thus disconnecting socket S6 from the 110 volt A.C. powersupply.

' Room lamp 11 is thus extinguished.

Strobe switch SW2 has a spring-loaded pushbutton which, when depressed,will momentarily energize relay coil D and momentarily illuminate lampL2, thus momentarily interrupting the power to socket S6. The strobeswitch is used to flash the room light on and off rapidly to produce astroboscopic effect to facilitate the elicitation of after-images forthe purpose of testing anomalous retinal correspondence.

In the event that the examiner wishes to utilize the projector or thehigh intensity lamp, the switches associated with these instrumentswould be depressed before the "off button P89 is depressed to extinguishroom light 11. When the lamp" pushbutton P86 is depressed, 12 volts A.C.is applied across lamp L6 illuminating the pushbutton and the power linevoltage is applied across contacts 1 and 2 of this switch, thus poweringsocket S9. Similarly, depression of projector pushbutton PB7 willilluminate the lamp associated with this pushbutton and apply 12 voltsto coil B closing contacts b and powering socket S8.

Assuming again that only the power switch has been operated and thatroom light 11 is illuminated, operation of pushbutton PBS associatedwith dimmer switch SW8, will cause bridging of contacts 1 and 2, thusilluminating lamp L8 to show that this switch has been operated, andbridging of contacts 3 and 4 applying 12 volts A.C. across relay coil C.The energization of relay coil C will open normally closed contacts 0which will result in the insertion of a conventional SCR dimmer switchin series with socket S6. Adjustment of knob K ll will achieve thedesired control of the intensity of the illumination of the examiningroom. Note that the operation of pushbutton PB8 will open contacts 5 and6, thus removing relay coil D from the effect of any voltage present atnodes 24 and 25. In this manner, the operation of the dimmer switchoverrides the operation of of switch SW9 and strobe" switch SW2. As willbe seen later, the operation of the dimmer switch also will override theeffect of any voltage present at contact M of the socket S1.

Operation of the fixation, blinker, or muscle switches will apply 6volts A.C. across the appropriate sockets S3, S4, or S5. For example,the blinker light can be operated by the examiner upon depression ofpushbutton PB4. Operation of this switch closes contacts 1 and 2powering socket S5 with 6 volts A.C. and illuminating lamp L4 associatedwith this switch.

Turning now to the effect of removing any of instruments I1 through I6from the hangers on panel 15, reference is made to FIG. 7. The removalof instrument l1 closes switch SW12 which applies 12 volts A.C. acrossrelay coil E. In response to the energization of coil E, normally opencontacts e1, e2 and e3 are closed. The closing of contacts e1 applies 12volts A.C. to contact M of plug Pl which is directly connected to node25 as can been seen from inspection of FIG. 6. Consequently, when dimmerswitch SW8 is not operated, 12 volts A.C. is applied across relay coil Dwhen contacts e1 are closed, thus opening normally closed contacts d andextinguishing room lamp 11. The closing of contacts e2 applies 3 voltsthrough potentiometer Rl across socket S12 into which the power leads ofthe ophthalmoscope are plugged. The closing of contact e3 applies 12volts A.C. to contact H of plug Pl. This has the effect of poweringsocket S3 which turns on fixation lamp 14.

In summary, the circuit means associated with the hanger for theophthalmoscope will, first of all, power the instrument upon its removalfrom its hanger. In addition, the circuit means will also cause the roomlight to be extinguished and will turn on fixation light 14. When theophthalmoscope is returned to hanger l6, switch SW12 will open removingpower from relay coil E and opening relay contacts e1, e2 and e3. As aconsequence, the lamp of the ophthalmoscope will be extinguished,fixation light 14 will be extinguished, and power will be reapplied tosocket S6 as relay coil D is deenergized. Thus, the return of instrumentI1 to its hanger will restore the initial ambient lighting conditions.

When the retinoscope is removed from hanger 17, switch SW13 will beclosed applying 12 volts A.C. across relay coil F. As a consequence,normally open contacts fl, f2, and f3, will be closed. The closing ofcontacts fl will apply 12 volts A.C. to contact K of plug Pl which willresult in the application of 12 volts to node 27 and the energization ofrelay coil C. Normally closed contact will thus be opened switching thedimmer circuit in series with socket S6. The closing of contacts f2 willapply 6 volts A.C. to contact I of plug P1 thus applying 6 volts A.C.across socket S4 and turning on muscle light 13. The closing of contactsf3 will apply 3 volts A.C. through potentiometer R2 to socket S13. Thissocket is associated with the retinoscope I2 so that the closing ofcontacts f3 will power the lamp associated with this instrument. Insummary, the removal of instrument I2 from its hanger willsimultaneously power the lamp in the instrument, dim the room lights,and turn on muscle light 13.

Returning instrument I2 to its hanger will reopen switch SW13deenergizing relay coil F and opening contacts fl, f2 and )3. Theinitial ambient lighting conditions will thus be restored wheninstrument I2 is returned to its hanger. The removal of any instrumentI3, I4, I5 or I6, from its respective hanger will result in the closingof switch S14SW17 thus powering the lamp in the individual instruments.The intensity of the lamp associated an instrument is controlled by thesetting of the potentiometer which is controlled by the knob on panel15. For example, knob K6 is associated with potentiometer R6; androtation of this knob when instrument I6 is in use will change thesetting of the potentiometer and adjust the lamp intensity of thisinstrument.

When the examiner wishes to utilize the slit lamp I7 in his examination,pushbutton PB11 is depressed, thus connecting 1 volts A.C. appearing atterminals 1 and 2 of plug P10 across the lamp of this instrument. Inaddition, the closing of this pushbutton will also interconnectterminals 3 and 4 of plug P10. As can been seen from inspection of FIG.7, the interconnection of terminals 3 and 4 of socket S10 will apply 12volts A.C. to terminal K of plug Pl. As indicated previously, powerapplied to this terminal appears at node 27 and will energize relay coilC which opens normally closed contacts c and inserts the dimmer circuitin series with socket S6, thus resulting in dimming of room light ll.

The closing of switch SW18 when instrument I8 is removed from its hangeralso closes contacts 3 and 4 associated with this switch and bridgesterminals 3 and 4 of plug P11. When terminals 3 and 4 of socket S11 arebridged by the closing of switch SW18, 12 volts is applied to terminal Mof plug P1. This causes 12 volts A.C. to appear at node 25 as shown inFIG. 6; and I2 volts are applied across relay coil D. This results inthe energization of this coil, the opening of contacts d, and theextinguishing of room light 11.

Switch panel 21 also includes pushbutton P1310 for signalling the nurseor assistant outside the examination room. Operation of the pushbuttonassociated with this switch will apply 6 volts A.C. across terminals 28and 29 on terminal board 30 attached to panel 210. Wires connected tothese terminals run to a nurses station 31 to provide a suitableindication that the examiner is calling for the nurse or assistant.

The various voltages which are required for operation of the instrumentassociated with instrument panel 15 are provided for by terminal blocks32 shown schematically in FIG. 7. Each of terminal blocks 32, as shownin FIG. 2, includes a plurality of electrically connected socketsadapted to receive terminal pins attached to leads LLl-LL6. These leadsare individually associated with each of the various instruments asshown in FIG. 7. Each of the sockets associated with the terminal stripis electrically connected to a different tap on transformer T1. Thiswill provide voltages of 3V,

. 6V, 9V, and 12V and will permit any one of these volt- When pushbuttonPB11 is released, the connection between terminals 3 and 4 of socket S10is broken and relay coil C is deenergized resulting in the closing ofcontacts c and the shunting of the dimmer circuit. The illuminationprovided by lamp 11 is thus returned to its initial condition.

When the examiner wishes to utilize the indirect ophthalmoscope I8 andsuch instrument is removed from its hanger, contacts 1 and 2 of switchSW18'are closed applying the voltage appearing across terminals 1 and 2of plug P11 across lamp L18 indicating that this switch has been closedand across the terminals of socket S18 thus powering instrument [8. Notethat the voltage across terminals 1 and 2 is 9 volts A.C. PotentiometerR7 may be adjusted by the examiner to provide the desired intensity forthe lamp associated with instrument I8.

ages to be applied to the various sockets for the instruments.

Sometimes it is desirable to provide for operation of some of thepushbutton switches from a location remote from wall 10 where main panel21 is located. For example, it may be desirable to have remote operationof the dimmer circuit and the projector, as well as the operation of thethree lamps 12, 13 and 14. In such case, the circuitry contained in thechassis behind panel 21 and shown in detail in FIG. 6 may be modified inaccordance with the subject matter shown in FIG. 8 of the drawing; andrear panel 210 (FIG. 2) is provided with socket S2 which mates with plugP2 on the remote switch bar designated by reference numeral 40 in FIG.9.

The operation of switch SW1 in FIG. 8 bridging the two contacts in thisswitch energizes relay coil A and results in illumination of the lamp inthis switch and the closing of normally open contacts a1 and a2 in thesame manner as described in connection with FIG. 6. Thus, socket S6 isdirectly powered illuminating lamp 11, and sockets S8 and S9 areconditionally powered depending upon the operation of switch SW7 andswitch SW6. With the contact arms of the various switches in theposition shown in FIGS. 8 and 9, it can be seen that there will be 12volts A.C. on terminal pins V1 and W1 of plug P2 and socket S2. Inaddition, there will be 6 volts A.C. at terminals R1, T1, and U1, ofplug P2 and socket S2.

When the strobe switch SW2 is operated and the two contacts therein arebridged, the lamp associated with this switch is illuminated and 12volts is applied to node 50. As a consequence, 12 volts are appliedacross relay coil D causing it to be energized and contacts d to beopened thus depowering socket S6 and extinguish,-

ing the room light. When the push button associated with the strobeswitch is released, the contacts are unbridged and the relay coil D isdeenergized permitting the room light to go on again. When off switchSW9 is operated, the bridging of contacts 1 and 2 of this switch alsoapplies 12 volts to node 50. As described previously, this results inturning off light 11. The lamp associated with switch SW9 is illuminatedby the bridging of the other pair of contacts in this switch.

When dimmer switch SW8 is operated by the movement of the rotary arm onthis switch from contact 2 to contact 1 12 volts are applied across lampL8 of this switch, across relay coil X associated with this switch andacross lamp L8 of remote dimmer switch SW8. The energization of coil Xcloses normally open contacts x applying 12 volts across relay coil C.This has the effect of opening normally closed contacts c and switchingin dimmer switch SW11 in series with socket S6 thus permitting theintensity of the light of lamp 11 to be controlled by knob l 1. When thecontact arm of diammer switch SW8 is returned to engagement with contact2, the 12 volts is removed from each of the lamps in switches SW8 andSW8 as well as from relay coil X. The ambient lighting is thus returnedto its initial condition.

In the event the examiner is stationed at the remote location, and themovable contact arm of switch SW8 is rotated from engagement withcontact 1 to engagement with contact 2 while the movable arm in switchSW8 remains engaged with contact 2, 12 volts will also be applied acrosslamps L8 and L8 and across relay coil X. Thus, the room light may bedimmed by operation of either switch SW8 or SW8; and in either instanceof operation, the lamp in each switch will be illuminated to indicatethat the intensity of the room light is under the control of the dimmerswitch SW11.

When projector switch SW7 is operated by rotating the movable contactarm from engagement with contact 2 to contact 1, 12 volts will beapplied across lamp L7, relay coil B, and lamp L7 in remote switch SW7.In this case, the two lamps will be illuminated indicating that theprojector switch has been operated and contacts b will be closedapplying 110 volts A.C. across socket S8. The operation of remote switchSW7 can also be used to apply 12 volts across the relay coil B bychanging the position of the moveable switch arm. The switches SW3, SW4and SW5 are operated to power sockets S3, S4, and S5, ina similarmanner. These sockets may also be powered by the operation of remoteswitches SW3, SW4", and SW5.

In summary, the embodiment of the invention shown in FIGS. 8 and 9permits the examiner to control all of the sockets from either panel 21or from a remote location. Operation of the switches available at bothlocations will illuminate a lamp associated with the switch at theremote location as well as the corresponding switch at the main locationindicating that one of the switches has been operated.

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

What is claimed is:

1. In an eye examination room illuminated by a room .light, and having aplurality of portable electrical instruments for conducting eyeexaminations, a hanger panel in said room having a hanger associatedwith each instrument for holding the same when not in use, circuit meansassociated with each hanger for causing the associated instrument to bepowered only when it is removed from its hanger, first circuit means forsupplying power to said room light but operable to disconnect power fromsaid room light, circuit means associated with a first of said hangersincluding first contact means operated in response to removal of thefirst instrument from said first hanger, said first circuit means beingoperable in response to operation of said first contact means wherebyremoval of the first instrument from said first hanger powers the firstinstrument and turns off the room light.

2. Apparatus according to claim 1 including a first fixation light atone end of the room, and second circuit means operable to supply powerto said first fixation light, said second circuit means being operablein response to operation of said first contact means whereby removal ofthe first instrument from said first hanger also turns on said firstfixation light.

3. Apparatus according to claim 2 including a dimmer circuit associatedwith said first circuit means and operable to control the amount ofpower supplied to said room light, and a manually operable first switchfor simultaneously operating said dimmer circuit and de-operating saidfirst circuit means when said first circuit means is operated wherebyoperation of said first switch while the first instrument is removedfrom said first hanger turns on the room light at a controlledintensity.

4. Apparatus according to claim 3 wherein the circuit means associatedwith a second of said hangers includes second contact means operable inresponse to removal of the second instrument from said second hanger,said dimmer circuit being operated in response to operation of saidsecond contact means whereby removal of thesecond instrument from saidsecond hanger when said first instrument is held by said first hanger,powers said second instrument and turns on the room light at acontrolled intensity.

5. Apparatus according to claim 4 including a second fixation light, andthird circuit means operable to supply power to said second fixationlight, said third circuit means being operable in response to operationof said second contact means whereby removal of the second instrumentfrom said second hanger also turns on said second fixation light.

6. Apparatus according to claim 5 including a manually operable secondswitch cooperable with saidfirst switch for selectively operating saidfirst circuit means and turning off the room light when all of theinstruments are held in their respective hangers, operation of saidfirst switch subsequent to operation of said second switch causingde-operation of said first circuit means whereby the room light isturned on at a controlled intensity by operation of said first switchsubsequent to operation of said second switch.

7. Apparatus according to claim 6 including a benchtype instrument forexamining eyes having a control switch manually operable to turn-on theinstrument, and means responsive to operation of said control switch foroperating said first circuit means whereby turning on said bench-typeinstrument turns off the room light.

8. Apparatus according to claim including a third manually operableswitch for operating said second circuit means independently of theoperation of said first contact means.

9. Apparatus according to claim 7 including a fourth manually operableswitch for operating said third cir-' cuit means independently of theoperation of said second contact means.

10. In an eye examination rool illuminated by a room light, and having aplurality of portable electrical instruments for conducting eyeexaminations, a hanger panel in said room having a hanger associatedwith each instrument for holding the same when not in use, circuit meansassociated with each hanger for causing the associated instrument to bepowered only when it is removed from its hanger, first circuit means forsupplying power to said room light but operable to disconnect power fromsaid room light, the circuit means associated with a first of saidhangers including first contact means operated in response to removal ofthe first instrument from said first hanger, said first circuit meansbeing operable in response to operation of said first contact meanswhereby removal of the first instrument from'said first hanger powersthe first instrument and turns off the room light, a first fixationlight at one end of the room, and second circuit means operable tosupply power to said first fixation light, said second circuit meansbeing operable in response to operation of said first contact meanswhereby removal of the first instrument from said first hanger alsoturns on said first fixation light, a dimmer circuit associated withsaid first circuit means and operable to control the amount of powersupplied to said room light, a manually operable first switch forsimultaneously operating said dimmer circuit and de-operating said firstcircuit means when said first circuit means is operated wherebyoperation of said first switch while the first instrument is removedfrom said first hanger turns on the room light at a controlledintensity, said circuit means associated with a second of said hangersincluding second contact means operable in response to removal of thesecond instrument from said second hanger, said dimmer circuit beingoperated in response to operation of said second contact means wherebyremoval 'of the second instrument from said second hanger when saidfirst instrument is held by said first hanger, powers said secondinstrument and turns on the room light at a controlled intensity, asecond fixation light, and third circuit means operable to supply powerto said second fixation light, said third circuit means bieng operablein response to operation of said second contact means whereby removal ofthe second instrument from said second hanger also turns on said secondfixation light, a manually operable second switch cooperable with saidfirst switch for selectively operating said first circuit means andturning off the room light when all of the instruments are held in theirrespective hangers, operation of said first switch subsequent tooperation of said second switch causing de-operation of said firstcircuit means whereby the room light is turned on at a .controlledintensity by operation of said first switch subsequent to operation ofsaid second switch, a benchtype instrument for examining eyes having acontrol switch manually operable to turn-on the instrument, meansresponsive to operation of said control switch for operating said firstcircuit means whereby turning on said bench-type instrument turns offthe room light,

a third manually operable switch for operating said second circuit meansindependently of the operation of said first contact means, and a fourthmanually operable switch for operating said third circuit meansindependently of the operation of said second contact means.

1. In an eye examination room illuminated by a room light, and having aplurality of portable electrical instruments for conducting eyeexaminations, a hanger panel in said room having a hanger associatedwith each instrument for holding the same when not in use, circuit meansassociated with each hanger for causing the associated instrument to bepowered only when it is removed from its hanger, first circuit means forsupplying power to said room light but operable to disconnect power fromsaid room light, circuit means associated with a first of said hangersincluding first contact means operated in response to removal of thefirst instrument from said first hanger, said first circuit means beingoperable in response to operation of said first contact means wherebyremoval of the first instrument from said first hanger powers the firstinstrument and turns off the room light.
 2. Apparatus according to claim1 including a first fixation light at one end of the room, and secondcircuit means operable to supply power to said first fixation light,said second circuit means being operable in response to operation ofsaid first contact means whereby removal of the first instrument fromsaid first hanger also turns on said first fixation light.
 3. Apparatusaccording to claim 2 including a dimmer circuit associated with saidfirst circuit means and operable to control the amount of power suppliedto said room light, and a manually operable first switch forsimultaneously operating said dimmer circuit and de-operating said firstcircuit means when said first circuit means is operated wherebyoperation of said first switch while the first instrument is removedfrom said first hanger turns on the room light at a controlledintensity.
 4. Apparatus according to claim 3 wherein the circuit meansassociated with a second of said hangers includes second contact meansoperable in response to removal of the second instrument from saidsecond hanger, said dimmer circuit being operated in response tooperation of said second contact means whereby removal of the secondinstrument from said second hanger when said first instrument is held bysaid first hanger, powers said second instrument and turns on the roomlight at a controlled intensity.
 5. Apparatus according to claim 4including a second fixation light, and third circuit means operable tosupply power to said second fixation light, said third circuit meansbeing operable in response to operation of said second contact meanswhereby removal of the second instrument from said second hanger alsoturns on said second fixation light.
 6. Apparatus according to claim 5including a manually operable second switch cooperable with said firstswitch for selectively operating said first circuit means and turningoff the room light when all of the instruments are held in theirrespective hangers, operation of said first switch subsequent tooperation of said second switch causing de-operation of said firstcircuit means whereby the room light is turned on at a controlledintensity by operation of said first switch subsequent to operation ofsaid second switch.
 7. Apparatus according to claim 6 including abench-type instrument for examining eyes having a control switchmanually operable to turn-on the instrument, and means responsive tooperation of said control switch for operating said first circuit meanswhereby turning on said bench-type instrument turns off the room light.8. Apparatus according to claim 5 including a third manually operableswitch for operating said second circuit means independently of theoperation of said first contact means.
 9. Apparatus according to claim 7including a fourth manually operable switch for operating said thirdcircuit means independently of the operation of said second contactmeans.
 10. In an eye examination rool illuminated by a room light, andhaving a plurality of portable electrical instruments for conducting eyeexaminations, a hanger panel in said room having a hanger associatedwith each instrument for holding the same when not in use, circuit meansassociated with each hanger for causing the associated instrument to bepowered only when it is removed from its hanger, first circuit means forsupplying power to said room light but operable to disconnect power fromsaid room light, the circuit means associated with a first of saidhangers including first contact means operated in response to removal ofthe first instrument from said first hanger, said first circuit meansbeing operable in response to operation of said first contact meanswhereby removal of the first instrument from said first hanger powersthe first instrument and turns off the room light, a first fixationlight at one end of the room, and second circuit means operable tosupply power to said first fixation light, said second circuit meansbeing operable in response to operation of said first contact meanswhereby removal of the first instrument from said first hanger alsoturns on said first fixation light, a dimmer circuit associated withsaid first circuit means and operable to control the amount of powersupplied to said room light, a manually operable first switch forsimultaneously operating said dimmer circuit and de-operating said firstcircuit means when said first circuit means is operated wherebyoperation of said first switch while the first instrument is removedfrom said first hanger turns on the room light at a controlledintensity, said circuit means associated with a second of said hangersincluding second contact means operable in response to removal of thesecond instrument from said second hanger, said dimmer circuit beingoperated in response to operation of said second contact means wherebyremoval of the second instrument from said second hanger when said firstinstrument is held by said first hanger, powers said second instrumentand turns on the room light at a controlled intensity, a second fixationlight, and third circuit means operable to supply power to said secondfixation light, said third circuit means bieng operable in response tooperation of said second contact means whereby removal of the secondinstrument from said second hanger also turns on said second fixationlight, a manually operable second switch cooperable with said firstswitch for selectively operating said first circuit means and turningoff the room light when all of the instruments are held in theirrespective hangers, operation of said first switch subsequent tooperation of said second switch causing de-operation of said firstcircuit means whereby the room light is turned on at a controlledintensity by operation of said first switch subsequent to operation ofsaid second switch, a bench-type instrument for examining eyes having acontrol switch manually operable to turn-on the instrument, meansresponsive to operation of said control switch for operating said firstcircuit means whereby turning on said bench-type instrument turns offthe room light, a third manually operable switch for operating saidsecond circuit means independently of the operation of said firstcontact means, and a fourth manually operable switch for operating saidthird circuit means independently of the operation of said secondcontact means.